The American Fuel & Petrochemical Manufacturers (AFPM) said on Wednesday it has filed a lawsuit challenging the U.S. environment regulator's biofuels policy, the latest industry body to join a legal battle over the controversial program.

The organization, which represents oil companies, said the petition to the U.S. Court of Appeals is targeting the Environmental Protection Agency's rulemaking around the Renewable Fuels Standards from 2014-2016.

Last month, biofuel and agriculture groups did the same, kicking off a widely-expected legal review of the policy.

On Friday, Feb. 5, DuPont filed a motion to intervene in the lawsuit. The company argues that the final volume requirements jeopardizes its cellelosic ethanol investments. DuPont is in the process of launching its commercial cellulosic ethanol production at its plant in Nevada, Iowa.